One of Mark and Marci Peden’s 130-acre sunflower fields under center pivot irrigation averaged 4,500 lbs/acre in 2002, with oil ranging between 43-45%. With a price and oil premium at about $13/cwt, the field grossed about $600/acre.

In 2001, the Pedens had irrigated sunflower that yielded over 3,500 lbs/acre on their farm north of Goodland, Kans. But 4,500 lbs/acre is a yield breakthrough for the Pedens, all the more amazing given last year’s parched and scorched growing conditions in the High Plains, where failed irrigated corn was common in some areas as low well capacity couldn’t keep up with the evaporative water demands of a thirsty corn crop.

The Pedens are pleased—but not surprised— at their seemingly unbelievable sunflower yield results.

“You just have to treat a 4,000-pound sunflower crop the same way you do a 250-bushel corn crop,” Mark says. “You have to pay attention to small details, and make every last acre count.”

Pioneer 63M91 was the variety the Pedens grew on their bin-busting sunflower

field last year. All of their sunflower in 2002 was irrigated to a varying degree. The Pedens, who have been growing sunflower for about 15 years, dropped seed for a 23,500 plant population, with the goal of a 22,000 plant population at harvest. They usually plant sunflower around May 20—weeks before many in the High Plains often plant the crop. Planting early helps sunflower plants pack on the bushels, and pour on the oil content, Mark explains.

“We sampled every other truck, and we were usually around 44 to 45% oil. The oil premium makes a difference in price, and you don’t have near the oil content if you plant at mid June,” he says. “The only downside to planting early is that you’re at risk to stem weevils. But those are easy to take care of with a pint of Furadan.”

Peden takes soil samples to three feet, and accounts for the residual nitrogen. Sunflower’s ability to use residual nutrients is a benefit to a corn-sunflower rotation, he says. “Corn sends roots down about three to four feet, and sunflower seven to eight feet. Whatever N leaches down beyond corn the sunflower will get the following year.”

He fertilizers with a yield goal of 4,000 lbs, putting down 190 lbs of N and 60 lbs of phosphorus before planting, and six gallons/acre of 10-34-0 along with a 10-inch band of Spartan and Prowl at planting.

They plant sunflower in 36-inch rows. “We need wide rows to keep the cultivator in the row, since we have terraces on some of the ground we farm,” says Mark. The Pedens cultivate sunflower once, when the plants are about two feet tall. “In our opinion, cultivating sunflower makes all the difference in the world. It has an amazing effect. We’ve never had a weed problem in our sunflower. A person just has to pay attention, and get every weed that’s out there.”

As one person cultivates, another follows up the row with a second tractor pulling an inter-row subsoil ripper (or “Sub-Tiller II,” as Blu-Jet, the manufacturer out of Thurston, Neb., calls it.). The Pedens swear by it. The ripper loosens and breaks up hard pan soil and helps with infiltration of the irrigation water, preventing surface runoff as well. The sub-tiller lifts and fractures the soil about 10” deep, while leaving the soil surface virtually undisturbed.

Mark attached prop blades to the back of each ripper shank. Set at a 45-degree angle to the ripper shanks, the blades form divots about 18” apart down each row, creating tiny water reservoirs or dams at a 45 degree angle to the row that keeps water from running down the ripper marks. The blades help to promote deeper root growth and to allow moisture to permeate and remain in the subsoil. The angle of the divots makes it easier for tractors and harvesting equipment to travel through the field, with less bounce. The Pedens use this equipment in their corn too; Mark says it makes a 30-40 bu/ac yield difference.

Last year the Pedens sprayed Furadan 4F on July 19 to control stem weevils, when sunflower was around the V8 stage, and a tank mix of Asana at 9 oz. and a ½ pint of methyl parathion on August 8, close to bloom, to treat seed weevils and head moths. They haven’t had to contend with any disease problems.

With the exception of one pivot of Roundup-Ready soybeans, the Pedens ran 10 center irrigation pivots of corn and sunflower last year. “I put the beans where I have weed problems, so we can clean it up with the Roundup,” says Mark. They also run several hundred acres of mostly corn and sunflower under flood irrigation, and dryland wheat. Well capacity varies; the pivot of sunflower that yielded 4,500 lbs was about 800 gal/minute. One pivot of milo and sunflower, which Mark says pumped water at “a super minimum well capacity,” still averaged 3,000 lbs. Across the farm, the Pedens sunflower yield averaged 3,800 lbs/acre last year.

The Pedens use a moisture probe and an agronomist to help assess their irrigation watering needs. Last year, they irrigated the soil profile with about 1 ¼” of water prior to planting, then about 3” around June 1, when the sunflower was about a foot tall. They applied another 4” when the sunflower crop is budding, followed by another 4” when the crop was blooming, and then another 2” late August to help with seed fill, with the final watering prior to plant maturity or about when the pedals dropped.

Because of the drought, the Pedens’ irrigation schedule last year was more intensive than usual. “Normally we’d cut that back about 2-3” or so in the middle of the growing season, and make use of the in-season moisture when we can. But we got absolutely no rain until the end of August,” says Mark.

Their sunflower last year reached maturity around September 10-15. They harvested the sunflower at 12% moisture, then binned and aerated the harvested crop. It took about 2 to 2 ½ days for the sunflower to dry down to an acceptable storage moisture level of 10%.

The Pedens manage their corn knowing that the sunflower crop the previous year will likely have utilized a good share of soil nutrients and soil moisture. They soil sample before rotating back to corn to determine how much fertilizer will be needed, and start their pivots a bit sooner in the spring to fill the soil moisture profile.

Mark says his sunflower seems to yield better under pivot irrigation, compared to flood. Center pivot irrigation results in a more efficient, more uniform application of water, he surmises, that doesn’t overly soak the root systems of sunflower plants. This observation has also been made in research literature, says Rob Aiken, crop scientist at the Kansas State University Northwest Research Extension Center in Colby, Kans. “During the flowering period, the sunflower crop can be sensitive to too much water and a lack of oxygen in the soil,” Aiken says.

Roger Stockton, KSU extension crops and soils specialist, says that while the Pedens’ sunflower yield results are not typical, it is indicative of the crop’s performance capabilities. He points out that some irrigated KSU sunflower plots yielded close to 4,000 lbs/acre last year. “It just goes to show that the crop is well acclimated here, and to our climate,” he says. – Tracy Sayler